Method and apparatus for forming flexible hollow tubing



March 15, 1966 D. FRIEDWALD ET AL 3,240,645

METHOD AND APPARATUS FOR FORMING FLEXIBLE HOLLOW TUBING Filed March 19, 1963 Fig. 1

United States Patent 3,240,645 METHOD AND APPARATUS FOR FORMING FLEXIBLE HOLLOW TUBING David Friedwald, Bronx, N.Y., Jacob Greenspan, Rego Park, N.Y., and Henry James Zcrnay, 3738 83rd St, Jackson Heights, Queens, N.Y., assignors, by direct and mesne assignments, to said Henry James Zernay Filed Mar. 19, 1963, Ser. No. 266,428

, Claims. (Cl. 156195) g This invention relates generally to the field of plastic extrusion, and more particularly to an improved means and method for forming flexible hollow tubing of a semirigid nature suitable for use in conjunction with the conducting of air at slightly above atmospheric pressure. Tubes of this type have application in such diverse devices as hair cleaners, vacuum tubes, breathing apparatuses, and the like. This type of tubing is characterized in that there is provided a spirally-arranged relatively rigid structure resembling a large coil spring, this structure being surrounded by relatively thin flexible material. This construction permitsflexibility along the length of the tube, but resists radial collapse which would interfere with the fiow of air through the tube.

. It'is among the principal objects of the present invention to provide an irnproved method of forming articles of the above type in which the tubular shape is obtained by spirally winding a strip of extruded synthetic resinous material having the reinforcing member incorporated therein in a spiral fashion to at least partially overlap the previously formed convolution while the extruded material is in a semi-molten state, so that the extruded strip, in spiral form, may be continuously integrated with convolutions already formed.

A' feature of the invention lies in the ready adaptability of existing machinery to perform the inventive method disclosed herein.

Another feature of the invention lies in the extremely high rate of production which may be obtained as contrasted with prior methods of fabrication of similar articles.

These objects and features, as well as other incidental ends and advantages, will more fully appear in the progress of the following disclosure, and be pointed out in the appendedclaims.

In the drawing, to which reference will be made in the specification, similar reference characters have been employedto designate corresponding parts throughout the several views.

FIGURE 1 is a plan view of an embodiment of the invention.

FIGURE 2 is a fragmentary side elevational view of the embodiment.

FIGURE 3 is a fragmentary enlarged plan view corresponding to the central portion of FIGURE 1.

FIGURE 4 is a fragmentary longitudinal sectional view as seen from the plane 44 in FIGURE 3.

FIGURE 5 is an enlarged transverse sectional view as seen from the plane 5-5 in FIGURE 1.

FIGURE 6 is a fragmentary plan view corresponding to FIGURE 3, but showing the removal of a completed article of manufacture.

FIGURE 7 is an enlarged fragmentary sectional view as seen from the plane 7--7 in FIGURE 6.

In accordance with the invention, there is illustrated in FIGURES l and 2 a conventional synthetic resinous extruding device, generally indicated by reference character 8. The extruding device includes a relatively fixed base 9, a mixing chamber 10 fed by a hopper element 11, and a source of motive power 12. A heated extruding member 13 projects outwardly from the mixing chamber 10 and is provided with a side exit 14. The specific details of the device 8 form no part of the present disclosure, being entirely conventional and well-understood in the art.

Extending through the member 13 is a continuous bore 15, and positioned opposite the bore is a supply of wirelike reinforcing material 16, a continuous segment 17 of which extends through the bore 15 to the point of extrusion at the side exit 14. The wire-like material may be actual metallic wire, or previously extruded relatively strong synthetic resinous material having a melting temperature above the temperature of operation of the device 8. We have found polypropylene to be suitable where the material extruded from the device 8 is of a lower melting point, as, for example, polyvinyls. v

Positioned adjacent the exit 14 of the device 8 is a spindle-supporting element 19, including a relatively fixed bed 20 having a movable carriage 21 thereon and means for simultaneously rotating an elongated spindle 22.

The bed 20 resembles in most respects the relatively fixed bed of a conventional engine lathe, and includes a pair of ways 24 joined by interconnecting members 25 and supported at a proper level with respect to the extruding device 8 by supporting legs 26 which may rest upon a floor (not shown) or horizontal surface.

The carriage 21 includes way-engaging members 29 and a prime mover 30, preferably in the form of a fractional horsepower electric motor. Switch means 31 provides for rotation of the prime mover 30 in either of two opposite directions of rotation, as well as an off position. The prime mover 30 is connected by an output shaft to a gear-reduction means 32, which simultaneously rotates a driven shaft 33 upon which the spindle 22 is connected, and a second driven shaft 34 having worm gear means 35 engaging a fixed lead screw 37 on the bed 20. The ratios of the gears involved are such that as the prime mover 30 operates at normal speed, the spindle 22 will rotate at a peripheral speed directly corresponding to the linear speed of extrusion from the device 8, and the carriage 21 will move either leftwardly or rightwardly as seen in FIGURES 1 and 2 at a speed which will permit a degree of overlap of successive convolutions of extruded material thereupon.

The spindle 22 is formed of hollow tubular metallic stock, and is engaged at a first end 39 to be supported in a substantially horizontal plane. The free end 40 may be slightly chamfered to facilitate removal of formed extrusions. A hollow longitudinal bore 41 extends substantially the entire length of the spindle 22, and communicates with the outer surface of the spindlethrough a series of transverse openings 42. The outer surface 43 is preferably smoothly polished, so as to afford mini mum friction preventing the ultimate removal of the synthetic resinous material wound thereupon. Connected through a universal rotational joint 44 is an air hose 45, its opposite end being connected to a source of compressed air (not shown) for periodically injecting air into the spindle 22 to flow through the holes 42.

Operation Operation is commenced by extruding a molten web 47 of generally planar configuration about a segment 46 of the reinforcing material. The free end of the web 47, being in semi-molten state, is preferably manually grasped by a clamping tool (not shown), and led around the outer surface 43 of the mandrel or spindle 22 adjacent the free end 40. The prime mover 30 is immediately started in the direction of rotation, which will result in a clockwise rotation of the spindle 22, as seen from the righthand portion of FIGURES 1 and 2. During this rotation, the carriage 21 will move rightwardly under the coaction of the worm gear means 35 with the lead screw 37. As the lead on the screw 37 is less than the width of the web 47 as measured between first and second side edges 48 and 49 thereof (see FIGURE the result will be an overlapping spiral, best seen in FIGURE 3. The sectional view of FIGURE 5 shows the formation of two wing portions on opposite sides of the web 47 between the reinforcing material 46 and the side edges 48, 49 respectively. The overlapped portions of web will fuse such that adjacent convolutions become integral forming a complete tube 50, and, when sufliciently cool, the web will remain in sealed and coiled condition. This operation is continued until the desired length of tubing 50 has been obtained, or until the area adjacent the mounted end 39 has been reached, at which time the prime mover 30 is stopped, and the wound web detached by cutting from the material still emanating from the device 8. Air is then injected into the bore 41 to travel through the air holes 42 to assist in loosening the now-completed tube 50 from the outer surface 43 of the spindle 22, following which the completed tube may be moved rightwardly as seen in FIGURE 6 to detach the same from the spindle. As stated above, in normal operation, fusing will occur shortly after the overlapping of the respective turns of the web 47; however, it will be understood that if fusing or solidification does not immediately occur, a suflicient amount of time is allowed to pass prior to removing the material to ensure joining of the overlapped areas. The operation is then repeated, commencing at an area adjacent the mounted end 39, and the prime mover 30 operated in reverse direction until the free end 40 is again positioned adjacent the exit 14, thus completing a second segment of tubing.

Where high production is necessary, it may be desirable to provide a pair of spindles (not shown), which are employed in alternate fashion, so that each spindle will have adequate time to cool before a subsequent winding operation is commenced. This modification (not shown) may be accomplished by providing driven turret means connected to the prime mover 30, as opposed to the single headstock arrangement illustrated in the drawing.

We wish it to be understood that we do not consider the invention limited to the precise details of structure shown and set forth in this specification, for obvious modifications will occur to those skilled in the art to which the invention pertains.

We claim:

1. An apparatus for forming hollow flexible tubing comprising an extruder for extruding a continuous strip of material along a material flow path, a spindle having a diameter substantially equal to the internal diameter of the hollow flexible tubing, means suppporting said spindle at a first end thereof, the other end of said spindle being free, rotational movement means at said one end of said spindle and operatively connected thereto for rotating said spindle about its own axis, linear movement means at said one end of said spindle and connected thereto for translating said spindle along its own axis and substantially perpendicular to the material flow path of said extruder, drive means for powering said rotational movement means and said linear movement means, said rotational movement means and said linear movement means being coordinated for rotation and translation of said spindle at a rate equal to the linear extrusion rate of said extruder when the extended strip of material is helically wound, in partially overlapped orientation, on said spindle, and reversing means for simultaneously reversing the direction of translation of said carriage means and the rotation of said spindle.

2. An apparatus for forming hollow flexible tubing comprising an extruder for extruding a continuous strip of material along a material flow path, a spindle having a diameter substantially qual to the internal diameter of the hollow flexible tubing, means supporting said spindle at a first end thereof, the other end of said spindle being free, means at said one end mounting said spindle for rotational movement about its own axis, a carriage mounting said rotational movement means and said spindle for translation parallel to the axis of said spindle and substantially perpendicular to the material flow path of said extruder, and drive means for powering said rotational movement means and said translation carriage means, said rotational movement means and said carriage translation means being interconnected for rotation and translation of said spindle at a rate equal to the extrusion rate of said extruder when the extended strip of material is helically wound, in partially overlapped orientation, on said spindle.

3. An apparatus for forming hollow flexible tubing comprising an extruder for extruding a continuous strip of material along a material flow path, a spindle having a diameter substantially equal to the internal diameter of the hollow flexible tubing, means supporting said spindle at a first end thereof, the other end of said spindle being free, means at said one end mounting said spindle for rotational movement about its own axis, a carriage mounting said rotational movement means and said spindle for translation parallel to the axis of said spindle and substantially perpendicular to the material flow path of said extruder, drive means for powering said rotational movement means and said translation carriage means, said rotational movement means and said carriage translation means being interconnected for rotation and translation of said spindle at a rate equal to the extrusion rate of said extruder when the extended strip of material is helically wound, in partially overlapped orientation, on said spindle, and reversing means for simultaneously reversing the direction of translation of said carriage means and the rotation of said spindle.

4. An apparatus for forming hollow flexible tubing comprising an extruder for extruding a continuous strip of material along a material flow path, a spindle having a diameter substantially equal to the internal diameter of the hollow flexible tubing, means supporting said spindle at a first end thereof, the other end of said spindle being free, means at said one end mounting said spindle for rotational movement about its own axis, a carriage mounting said rotational movement means and said spindle for translation parallel to the axis of said spindle and substantially perpendicular to the material flow path of said extruder, drive means for powering said rotational movement means and said carriage translation means, said rotational movement means and said carriage translation means being interconnected for rotation and translation of said spindle at a rate equal to the extrusion rate of said extruder when the extended strip of material is helically wound, in partially overlapped orientation on said spindle, reversing means for simultaneously reversing the direction of translation of said carriage means and the rotation of said spindle, said spindle being hollow and having a series of radial air passage openings formed therein, and air pressure means connected to said spindle for injecting air into said spindle and through said openings for aiding in the removal of a finished length of hollow tubing from said spindle.

5. The process of manufacturing flexible hollow tubing of synthetic resinous material comprising the steps of extruding a strip of synthetic resinous material having at least one wing portion at a controlled linear rate, securing said strip to a cylindrical surface, rotating said cylindrical surface about its central axis in a first rotational direction and translating said cylindrical surface along said central axis in a first linear direction at rates complementary to the controlled linear extrusion rate, forming said strip of linear material into an overlapped helix on said cylindrical surface with each turn of said strip of linear material at least partially overlapping the wing portion of the previously applied turn, removing said helically overlapped material from said cylindrical surface after it has cooled and solidified into a first hollow tubing, securing a further portion of said strip to said cylindrical surface, rotating said cylindrical surface about its central axis in a second rotational direction opposite from said first rotational direction and translating said cylindrical surface along said central axis in a second linear direction opposite from said first direction at rates complementary to the controlled linear extrusion rate,

and forming a second hollow tubing in the manner stated 10 above for the first hollow tubing.

References Cited by the Examiner UNITED STATES PATENTS Schrank 156344 Ferguson et a1. 156187 XR Beare et a1. 156244 XR Meissner 156-244 XR Roberts et al. 156143 XR EARL M. BERGERT, Primary Examiner.

P, DIER, Examiner. 

5. THE PROCESS OF MANUFACTURING FLEXIBLE HOLLOW TUBING OF SYNTHETIC RESINOUS MATERIAL COMPRISING THE STEPS OF EXTRUDING A STRIP OF SYNTHETIC RESINOUS MATERIAL HAVING AT LEAST ONE WING PORTION AT A CONTROLLED LINEAR RATE, SECURING SAID STRIP TO A CYLINDRICAL SURFACE, ROTATING SAID CYLINDRICAL SURFACE ABOUT ITS CENTRAL AXIS IN A FIRST ROTATIONAL DIRECTION AND TRANSLATING SAID CYLINDRICAL SURFACE ALONG SAID CENTRAL AXIS IN A FIRST LINEAR DIRECTION AT RATES COMPLEMENTARY TO THE CONTROLLED LINEAR EXTRUSION RATE, FORMING SAID STRIP OF LINEAR MATERIAL INTO AN OVERLAPPED HELIX ON SAID CYLINDRICAL SURFACE WITH EACH TURN OF SAID STRIP OF LINEAR MATERIAL AT LEAST PARTIALLY OVERLAPPING THE WING PORTION OF THE PREVIOUSLY APPLIED TURN, REMOVING SAID HELICALLY OVERLAPPED MATERIAL FROM SAID CYLINDRICAL SURFACE AFTER IT HAS COOLED AND SOLIDIFIED INTO A FIRST HOLLOW TUBING, SECURING A FURTHER PORION OF SAAID STRIP TO SAID CYLINDRICAL SURFACE, ROTATING SAID CYLINDRICAL SURFACE ABOUT ITS CENTRAL AXIS IN A SECOND ROTATIONAL DIRECTION OPPOSITE FROM SAID FIRST ROTATIONAL DIRECTION AND TRANSLATING SAID CYLINDRICAL SURFACE ALONG SAID CENTRAL AXIS IN A SECOND LINEAR DIRECTION OPPOSITE FROM SAID FIRST DIRECTION AT RATES COMPLEMENTARY TO THE CONTROLLED LINEAR EXTRUSION RATE, AND FORMING A SECOND HOLLOW TUBING IN THE MANNER STATED ABOVE FOR THE FIRST HOLLOW TUBING. 